Field of the Invention
The present disclosure relates to an organic light emitting display device, and more particularly, to an organic light emitting display device including a voltage supply line structure which can improve luminance uniformity of the organic light emitting display device by reducing a deviation in a potential difference between an anode and a cathode depending on a position of an active area of the organic light emitting display device when the organic light emitting display device is enlarged.
Description of the Related Art
As the age of information technology has proceeded, the field of display devices for visually displaying electrical information signals has grown rapidly. Thus, studies for developing technologies, such as thinning, weight lightening, and low power consumption, of various flat panel display devices have continued. Representative examples of the flat panel display devices include a Liquid Crystal Display (LCD) device, a Plasma Display Panel (PDP) device, a Field Emission Display (FED) device, an Electro-Wetting Display (EWD) device, an Organic Light Emitting Display (OLED) device, and the like.
An organic light emitting display device is a self-light emitting display device that does not need a separate light source unlike a liquid crystal display, and thus, the organic light emitting display device can be manufactured in a lightweight and thin form. Further, the OLED is advantageous in terms of power consumption since it is driven with a low voltage. Also, the organic light emitting display device has excellent color expression ability, a high response speed, a wide viewing angle, and a high contrast ratio (CR). Therefore, the OLED has attracted attention as a next-generation display device.
An active area (AA) of the organic light emitting display device includes a plurality of sub-pixels. Each of the sub-pixels includes an organic light emitting diode (OELD). Each organic light emitting diode includes an anode, an organic light emitting layer, and a cathode. An anode voltage ELVDD is supplied to the anode, and a cathode voltage ELVSS is supplied to the cathode.
If the organic light emitting display device is of a top-emission type, the cathode uses a transparent or translucent electrode in order to upwardly emit light emitted from the organic light emitting layer. The cathode is formed to have small thickness in order to secure transparency. Therefore, resistance of the cathode becomes very high.
In order to secure the reliability of the display device, an encapsulation part configured to protect the organic light emitting layer against moisture, a physical shock, or impurities which may be generated during a manufacturing process is formed on an organic light emitting element including the organic light emitting layer. In the top-emission organic light emitting display device, a glass encapsulation part, or an encapsulation part having a thin film encapsulation structure in which an inorganic encapsulation layer and an organic layer for delaying infiltration of moisture is used as the encapsulation part.
As a size of the top-emission organic light emitting display device is increased, a length of a line for supplying a voltage is also increased. A line resistance applied to each of the sub-pixels is increased in proportion to the length of the line. Therefore, there is a difference in voltage transmitted along the line for each sub-pixel. Accordingly, luminance uniformity of the organic light emitting display device is decreased.